The objective of this Phase I SBIR is to prototype a new design for a low impedance electrode for use in implantable systems. Lower impedance electrodes reduce the power requirements for such systems, which in turn can lead to prolonged battery life and/or smaller implant packages. This design relies on implementing novel geometries which change the ratio of conductive area to perimeter. We feel our approach, which can be used with existing materials, can deliver significant benefits with relatively low risks. We are targeting a 50% reduction in electrode impedance. 1. We will model and build a set of planar electrodes. The outcome of this objective will be a model describing the predicted impedance as a function of certain geometric parameters. The model will help determine the configuration of a set of test articles to be used in objective 2. 2. The second specific aim is to measure in vitro the impedance of control and test electrodes as a function of electrode area and electrode perimeter. The impedance data will be used to test the hypothesis that increasing electrode perimeter for a given area decreases electrode impedance and to inform the design of electrodes in objective 3. It will also be used to refine the model generated in Objective 1. 3. Based on the data obtained from the in vivo testing of the planar electrodes, we will model and then fabricate prototype cylindrical electrodes. We will use the data from our model based analysis and from the test results of the planar electrodes to guide our choices of edge geometries for the cylindrical conductive segments. A significant part of this objective is confirming that we have an analytic approach to predicting the impedance performance of the electrode before it is manufactured. 4. We will perform a circuit analysis, based on public specifications, of several IPGs to characterize the positive effect on battery life of a reduced impedance electrode. [unreadable] [unreadable]